Liquid crystal display devices are widely used as display devices of smartphones, tablet computers, car navigation systems and the like. In general, a liquid crystal display device comprises a liquid crystal panel and an illumination device which is overlaid on the rear surface of the liquid crystal panel and illuminates the liquid crystal panel. The illumination device includes a frame (or bezel), a reflective layer, a light guide, an optical sheet (prism sheet, diffusion sheet), a light source device (light source unit) which supplies light to be emitted to the light guide, etc. The light source unit includes a wiring substrate such as an FPC and a plurality of light sources (such as light-emitting diodes or LEDs) mounted on the wiring substrate. The illumination device is fixed to the rear surface of the liquid crystal panel with, for example, a double-faced tape and is held at a predetermined position.
Recently, there has been a demand to further narrow the frame of the liquid crystal display device. In the case of narrowing the frame, the frame of the liquid crystal panel and the frame of the illumination device need to be narrowed, but also the dimension margin of each component needs to be reduced. In this case, the size of the light guide may become smaller than the size of the display area of the liquid crystal panel. In the above-described design, light is emitted from an edge portion of the light guide, and an edge of the light guide becomes abnormally luminous. Accordingly, a frame peripheral portion of the display area will be brightly illuminated.